Delegates:Using Delegates : delegate « Language Basics « C# / C Sharp

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Delegates:Using Delegates

/*
A Programmer's Introduction to C# (Second Edition)
by Eric Gunnerson

Publisher: Apress  L.P.
ISBN: 1-893115-62-3
*/
// 22 - Delegates\Using Delegates
// copyright 2000 Eric Gunnerson
using System;


public class DelegatesUsingDelegates
{
    public static void Main()
    {
        Container employees = new Container();
        // create and add some employees here
        
        // create delegate to sort on names, and do the sort
        Container.CompareItemsCallback sortByName = 
        new Container.CompareItemsCallback(Employee.CompareName);
        employees.Sort(sortByName);            
        // employees is now sorted by name
    }
}

public class Container
{
    public delegate int CompareItemsCallback(object obj1, object obj2);
    public void Sort(CompareItemsCallback compare)
    {
        // not a real sort, just shows what the
        // inner loop code might do
        int x = 0;
        int y = 1;
        object    item1 = arr[x];
        object item2 = arr[y];
        int order = compare(item1, item2);
    }
    object[]    arr = new object[1];    // items in the collection
}
public class Employee
{
    Employee(string name, int id)
    {
        this.name = name;
        this.id = id;
    }
    public static int CompareName(object obj1, object obj2)
    {
        Employee emp1 = (Employee) obj1;
        Employee emp2 = (Employee) obj2;
        return(String.Compare(emp1.name, emp2.name));
    }
    public static int CompareId(object obj1, object obj2)
    {
        Employee emp1 = (Employee) obj1;
        Employee emp2 = (Employee) obj2;
        
        if (emp1.id > emp2.id)
        return(1);
        if (emp1.id < emp2.id)
        return(-1);
        else
        return(0);
    }
    string    name;
    int    id;
}


           
       

Related examples in the same category

1.	Define your own delegate
2.	Late Binding Delegates: A delegate is a repository of type-safe function pointers.
3.	illustrates the use of a delegate 2
4.	illustrates the use of a multicast delegate
5.	illustrates the use of a delegate that calls object methods
6.	Demonstrates a simple form of a delegate
7.	Demonstrates combining and removing delegates to create new delegates
8.	Demonstrate getting and printing the invocation list for a delegate
9.	Demonstrates adding multiple methods to a delegate
10.	Using a delegate with a container class to sort the collection and return a sorted array using different sort criteria
11.	Demonstrate using a static delegate without declaring an instance of the class
12.	A simple delegate example
13.	Delegates can refer to instance methods, too
14.	Two delegates
15.	The minimum implementation of a delegate
16.	Delegates to Instance Members
17.	Delegates:Multicasting
18.	Arrays of Delegates
19.	To remove delegates from a multicast delegate, use the Remove method, the minus operator (-), or the -= assignment operator.
20.	the syntax of the GetInvocationList method: delegate [] GetInvocationList()
21.	The publisher/subscriber relationship is a one-to-many relationship.
22.	Lifetime of outer variables is aligned with the delegate
23.	Combining delegates Multiple delegates are combined using the Combine method, the plus operator (+), or the += assignment operator.
24.	CreateDelegate and DynamicInvoke